Dialysis system with flow regulation device

ABSTRACT

A dialysis system includes a dialysis machine with a variable fluid demand including at least a lower demand and a higher demand. A fluid source is in fluid communication with the dialysis machine and provides fluid to the dialysis machine at a fluid flow rate. A flow regulation device includes a fluid inlet in fluid communication with the fluid source and a fluid outlet in fluid communication with the dialysis machine. The flow regulation device is operable to expand and contract to provide a variable internal volume. The flow regulation device expands when the dialysis machine has the lower demand and contracts when the dialysis machine has the higher demand.

BACKGROUND

The present disclosure relates generally to a dialysis system. Morespecifically, the present disclosure relates to a dialysis systemincluding a flow regulation device for regulating the fluid flow to adialysis device.

Hemodialysis uses a dialysis fluid to remove waste products from apatient's blood. One of the drawbacks of performing home hemodialysis(hemodialysis in a patient's home) is the need for a dedicated watertreatment, which includes equipment, water connection and drainage.Installing and using those components is a difficult and cumbersome taskthat can require a patient's home to be modified. Nevertheless, thereare benefits to daily hemodialysis treatments versus bi- or tri-weeklyvisits to a treatment center. In particular, a patient receiving morefrequent treatments removes more toxins, waste products, and excesswater more frequently, thus reducing fluctuations in blood chemistry andblood pressure, than a patient receiving less frequent but perhapslonger treatments.

Peritoneal dialysis utilizes a sterile dialysis solution, which isinfused into a patient's peritoneal cavity and into contact with thepatient's peritoneal membrane. Waste, toxins and excess water pass fromthe patient's bloodstream through the peritoneal membrane and into theused dialysate. The spent dialysate is later drained from the patient'speritoneal cavity to remove the waste, toxins and excess water from thepatient. Patients undergoing peritoneal dialysis also face difficultiesin terms of the volume of treatment fluid needed.

Dialysis machines require large (ranging from 20 to 200 liters pertreatment) amounts of water to provide the dialysis fluid used in themachine. Further, the fluid demand of a dialysis machine is not constantand varies with the cycling of the machine. In the institutionalsetting, most water systems for dialysis supply a hydraulic branch withvery large volumes of water. The excess water and large number ofindividual dialysis systems connected to the branch mitigate thevariable fluid demand of each individual machine. Moreover, many watersystems include large tanks capable of holding several thousand litersto provide a backup reservoir to account for changes in draw rate.

In a home setting, a single dialysis device may be connected to a singlewater supply without any fluid reservoir in the circuit. Thus, thedevice lacks the water reserve capabilities previously described forsystems with large numbers of dialysis machines. Because dialysismachines do not draw a constant flow of water but rather start and stop,problems are presented. The fluid supply to the device needs to have aflow capacity that is at least as great as the maximum instantaneousdraw rate of the dialysis device, which can be significantly greaterthan the average fluid demand of the dialysis device. Further, if thewater source provides a continuous flow of fluid, a significant amountof dialysis fluid is produced but not used for dialysis, and thus iswasted.

SUMMARY

The present disclosure provides a dialysis system including a flowregulation device for regulating the fluid flow to the dialysis device.

In an embodiment, a dialysis system includes a dialysis machine with avariable fluid demand including at least a lower demand and a higherdemand. A fluid source is in fluid communication with the dialysismachine and provides fluid to the dialysis machine at a fluid flow rate.A flow regulation device includes a fluid inlet in fluid communicationwith the fluid source and a fluid outlet in fluid communication with thedialysis machine. The flow regulation device is operable to expand andcontract to provide a variable internal volume. The flow regulationdevice expands when the dialysis machine has the lower demand andcontracts when the dialysis machine has the higher demand. The fluid maybe dialysate or purified water.

In an embodiment, the flow regulation device includes a first wall and asecond wall disposed opposite each other between the fluid inlet and thefluid outlet to define in part the internal volume, wherein the firstwall and the second wall are composed of a compliant material. The firstwall and the second wall move away from each other when the deviceexpands and move towards each other when the device contracts.

In another embodiment, the flow regulation device includes a pleatedwall, the pleated wall expanding outwardly to provide the variableinternal volume.

In an embodiment, the maximum internal volume of the flow regulationdevice is between 25 mL and 200 mL. The maximum internal volume of theflow regulation device may be between 50 ml and 100 ml.

In an embodiment, the fluid source comprises a system for preparing thefluid from a water source.

In an embodiment, the fluid flow rate from the fluid source is generallyconstant. The fluid flow rate from the fluid source may be generallyequal to an average fluid demand of the dialysis machine.

In an embodiment, the dialysis machine is a hemodialysis machine.

In another embodiment, a dialysis system includes a flow regulationdevice that contains a gas providing a gas volume. The gas volume isregulated to provide a variable fluid volume. The flow regulation deviceprovides a maximum fluid volume between 25 mL and 200 mL. The gas volumedecreases when the dialysis machine has the lower demand and increaseswhen the dialysis machine has the higher demand.

In an embodiment, the flow regulation device comprises a rigid canister.The gas volume may be regulated by discharging gas from the flowregulation device and taking gas into the flow regulation device. Thedialysis system may include a filter for filtering gas entering the flowregulation device.

In another embodiment, a dialysis system includes a dialysis machinewith a variable fluid demand. A fluid source is in fluid communicationwith the dialysis machine and provides fluid to the dialysis machine ata fluid flow rate. A controller is in communication with the dialysismachine and configured to send a control signal indicative of a fluiddemand of the dialysis machine. A flow control mechanism is incommunication with the controller and operable to receive the controlsignal to control the fluid flow rate based on the fluid demand of thedialysis machine.

In another embodiment, a method of controlling the flow of fluid to adialysis machine includes providing the dialysis machine. The dialysismachine has a variable fluid demand including at least a lower demandand a higher demand. A fluid source is in fluid communication with thedialysis machine and provides fluid to the dialysis machine. A flowcontrol mechanism is provided to control flow from the fluid source. Theflow of fluid to the dialysis machine is controlled by sending a signalfrom the dialysis machine, wherein the signal is indicative of a fluiddemand of the dialysis machine, and using the signal to regulate theflow control mechanism to control the fluid flow based on the fluiddemand of the dialysis machine.

In an embodiment, the signal is indicative of a current fluid demand ofthe dialysis machine. Alternatively, the signal is indicative of ananticipated future fluid demand of the dialysis machine.

In an embodiment, the dialysis machine includes a pump and a pumpcontroller, wherein the signal is provided by the pump controller. Thesignal may be provided by wire. Alternatively, the signal may beprovided wirelessly.

Additional features and advantages are described herein, and will beapparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 depicts a perspective view of a dialysis system.

FIG. 2 is an embodiment of a dialysis system including a system forpreparing dialysis solution.

FIG. 3 illustrates an embodiment of a flow regulation device in a firstconfiguration.

FIG. 4 illustrates the flow regulation device of FIG. 2 in a secondconfiguration.

FIG. 5 illustrates another embodiment of a flow regulation device.

FIG. 6 illustrates another embodiment of a flow regulation device.

DETAILED DESCRIPTION

The present disclosure is directed to a flow regulation device formaking dialysis easier for a dialysis patient at home. While theembodiments discussed are not limited to home applications, it will bereadily apparent that an efficient, safe, and conveniently-sizeddialysis system is most useful in a home application. Nevertheless, thesystems disclosed herein may also be used in larger institutions, suchas hospitals or clinics, and may be used as back-up or reserve capacityin the event that the supply chain is somehow interrupted.

A general hemodialysis system is depicted in FIG. 1. Patient P isundergoing hemodialysis with hemodialysis machine 20, which may be ahome hemodialysis machine. The patient is connected to the hemodialysismachine via tubing 12, arterial and venous access needles A_(N) andV_(N), and access site 14. The hemodialysis machine H pumps freshdialysate from a fluid source, which may be provided by the system forpreparing dialysis solution described below. Tubing 16 conveys freshdialysate from a dialysis source to a dialysate pump in the hemodialysismachine, and then to the dialyzer 18. A system for administeringperitoneal dialysis using fresh dialysate fluid may be used instead.

As shown in FIG. 2, the dialysis system includes a fluid source 10, aflow regulation device 20, and a dialysis machine 30. The fluid sourcemay be the system 60 (described below) for producing dialysis fluid, oranother suitable fluid source. Alternatively, the dialysis fluid can beproduced in the dialysis machine 30, and the fluid source may supply thedialysis machine 30 with purified water for dialysis. The dialysismachine 30 has a variable fluid demand. The fluid source 10 is in fluidcommunication with the dialysis machine 20 and provides dialysis fluidto the dialysis machine 30. When the dialysis system is in the no flowor lower flow parts of a pump cycle, the flow regulation device 20 isfilled with dialysis fluid or purified water from the fluid source 10.When the dialysis device 30 initiates the high flow portion of the pumpcycle, the volume of fluid in the flow regulation device 20 isdecreased. Thus, the flow regulation device 20 acts as a damper toreduce the pulsatility, or variations in fluid demand, that the fluidsupply 10 is exposed to.

One system 60 for producing dialysate to provide fluid for the dialysisfluid source 10 is depicted in FIG. 6. System 60 receives purified waterfor dialysis through line 61 a and control valve 61 b. The water isheated, if desired, using in-line heater 61. The heated water flowsthrough lines 61 c, 61 d to A and B concentrate pumps 62, 63, forpumping concentrate respectively from reservoirs 62 a, 63 a. The pumpsare positive displacement pumps, such as gear pumps, vane pumps, orpiston pumps, to pump precise amounts of A or B concentrate. Oneembodiment uses small ceramic piston pumps, available from FluidMetering, Inc., Long Island, N.Y., U.S.A. U.S.A. Other pumps may beused. Other embodiments use proportioning or ratiometric pumps, whoseflow of A or B concentrate may be set, and which thereafter pump A and Bconcentrate in a ratio proportional to the distilled water metered out.A controller for the system keeps track of the amounts of concentratepumped, and also keeps track of the amount of deaerated water and A thatis pumped, thus keeping precisely proportioned flows.

In this embodiment, the A concentrate pump 62 pumps A concentrate tomixing vessel 64 through line 62 a, the vessel not filled but retainingan air gap at its top, while the correct ratio of water also flows tothe vessel through line 61 e. After the water and the A concentrate aremixed, the mixture is deaerated by spraying using precision meteringpump 64 a, nozzle 64 c, and air trap 64 b. Other embodiments such as asimple restriction creating a starved intake to pump 64 a, could besubstituted for the sprayer to remove the air from the solution. Themixture is monitored by temperature and conductivity sensors 64 d, 64 e.Vessel 64 includes a level sensor L. The deaerated acid mixture is thensent to the B mix chamber 65, where B concentrate from the B concentratepump through line 63 b is added, in this case in-line. The B mix chamber65 is equipped with a second conductivity sensor 66 to monitor thequality of the finished dialysis solution.

The dialysis solution is then pumped by supply pump 67 through filter 67a, to remove particles larger than 150μ. Control valve 68 controls theflow of dialysis solution from system 60. If the correct level ofcontinuity has not been achieved, the freshly-prepared dialysis solutionmay be recycled as desired through the filter and the mixing chamber, asshown, until the proper mixing and purity has been achieved. Thedialysis solution can then be pumped through a final filter, endotoxinfilter 69, on its way to being used. The endotoxin filter is intended toremove endotoxins and bacteria, or fragments of bacteria, such as E.coli and P. aeruginosa. This filter could be an ultrafilter such asthose made by Medica Mirandolla Italy or a charged membrane microfiltersuch as those made by Pall, Long Island, N.Y., USA.

The process described above is only one method for preparing a dialysissolution. Other dialysis solutions may be used, including thoserequiring an osmotic agent, such as a small amount of dextrose, glucose,sodium or potassium polyacrylate, or mixtures of these, or othercomponent. These solutions are prepared in generally similar ways, someembodiments using powders, some using concentrates, some usingsolutions. Any such embodiments are intended to fall within the scope ofthe present disclosure. Embodiments using powders may require aconventional stirred-tank vessel, or vessel suitable for mixing powdersusing a stirrer or using flow, often turbulent flow, to insure a goodmixing. For home use, this may be any suitable mixer capable ofmaintaining and preserving sterility.

FIG. 3 shows an embodiment 40 of the flow regulation device. The flowregulation device 40 is disposed between the fluid source 10 and thedialysis machine 30. Flow regulation device 40 includes a fluid inlet 42in fluid communication with the fluid source 10 and a fluid outlet 44 influid communication with the dialysis machine 30. The flow regulationdevice 40 is operable to expand and contract to provide a variableinternal volume. The flow regulation device 40 expands when the dialysismachine 30 has a lower demand and contracts when the dialysis machine 30has a higher demand. FIG. 4 shows the flow regulation device 40 in asecond configuration with a larger internal volume 47 than the internalvolume 45 of the flow regulation device 40 in the first configurationshown in FIG. 3.

The flow regulation device 40 includes a first wall 46 and a second wall48 disposed opposite each other between the fluid inlet and the fluidoutlet. Walls 46, 48 define in part the internal volume 45. The walls46, 48 move away from each other when the device expands and towardseach other when the device contracts. The walls 46, 48 are composed of acompliant material so that they may expand and contract depending on theflow requirements of the dialysis device. Suitable compliant materialsinclude elastomers and plastics, such as natural rubber latex, PVC,polyurethane, or silicone.

The dialysis machine 30 may operate at a typical average flow rate of500 ml/min, but the given instantaneous demand rate may be between 0ml/min and 1000 ml/min. Thus, the lower fluid demand may be 0 ml/min,and the higher fluid demand may be 1000 ml/min. The fluid flow rate fromthe fluid source 10 is preferably generally equal to the averagedialysis fluid demand of the dialysis machine 30. The flow regulationdevice 40 may provide a maximum internal volume between 25 ml and 200ml, preferably between 50 mL and 100 mL. Thus, the flow regulationdevice 40 may provide for pulses of no flow and maximum flow of about6-10 seconds. In one embodiment, the dialysis machine provides a flowcycle of between 5 and 60 seconds of fluid demand, and between 0.5 and30 seconds of no fluid demand.

FIG. 5 illustrates another embodiment 50 of a flow regulation device.The flow regulation device 50 includes a fluid inlet 52 in fluidcommunication with the fluid source 10 and a fluid outlet 54 in fluidcommunication with the dialysis machine 30. The flow regulation device50 includes at least one pleated wall 56 and optionally a second pleatedwall 58. The pleats in the pleated walls 56, 58 allow the walls 56, 58to expand outwardly and contract inwardly to provide a variable internalvolume for the flow regulation device 50. The flow regulation device 50may be made of any suitable material, including elastomers, plastics,and so forth.

The flow regulation devices 40, 50 may be easily sanitized between uses.Because the inner surfaces of the flow regulation devices 40, 50 areexposed to fluid (which may be a disinfecting solution), it is easy toensure that the entire flow circuit has been disinfected.

FIG. 5 illustrates another embodiment 70 of a flow regulation device.Flow regulation device 70 includes a rigid container 76 to regulate therequired flow from the fluid source to the fluid demand of the dialysismachine. The container 76 includes dialysis fluid 71 in the bottomportion 75 and air or other gas 73 in the top portion 77. The level ofthe dialysis fluid 71 rises when the dialysis machine 30 has a lowerdemand and falls when the dialysis machine 30 has a higher demand anddraws fluid from the container 76. To accommodate the change in thevolume of the fluid 71, the air 73 also changes volume. To accommodatethe change in air volume, the air 73 may be compressed or expanded asappropriate. Alternatively, air 73 may be discharged to the exterior ofthe flow regulation device 70 and taken into the device 70 to controlthe air volume. The intake of air is preferably through a suitably ratedfilter or other mechanism to maintain the sterility of the system.

The systems described herein provide significant advantages over currentsystems. By using a flow regulation device, changes in draw rate aresmoothed so that the fluid supply 10 only needs to supply dialysis fluidat the average draw rate of the dialysis machine 30, not at the peakdraw rate. The flow regulation devices 40, 50, 70 take up very littlespace and do not require the large tank volumes of conventional systems.

In another aspect, a dialysis system 10 uses a flow control method toaccommodate the variations in fluid demand of the dialysis machine 30.The system includes a data connection between the dialysis machine 30and the fluid source 10. The data connection provides a signal from thedialysis machine 30 to the fluid source 10 to adjust the flow setting offluid from the fluid source 10. The flow setting may include a simpleon/off control or a more precise flow control. The signal may beindicative of a current fluid demand of the dialysis machine 30, or theanticipated future demand. The dialysis machine 30 may include a controlmechanism for its pumps. Based on the current and future flow need ofthe pumps, the dialysis machine 30 specifies the desired flow rate ofthe dialysis fluid. The output of the fluid source 10 is regulated tomeet the real-time demand of the dialysis machine 30.

For example, the dialysis machine 30 sends a command signal to a valveor other flow setting to open the valve or provide a certain flow rate.Dialysis fluid (or purified water) from the fluid source 10 is thenprovided at the desired flow rate. The fluid source 10 would typicallyproduce the fluid at the peak rate needed. When the fluid demand of thedialysis machine 30 is lowered, the dialysis machine 30 sends a commandto slow or stop the production of dialysis fluid. The dialysis systemmay be programmed to anticipate the demand of the dialysis machine 30 sothat there is no lag time between the dialysis fluid demand of thedialysis machine 30 and the desired flow rate of dialysis fluid from thefluid source 10. The connection between the dialysis machine 30 and thefluid source 10 may be provided by any type of data communication link,including wired, radio, infrared, Bluetooth, and the like.

In another embodiment, a system uses a fluid connection to conveyinformation from the dialysis machine 30 to the fluid source 10. Whenthe dialysis machine 30 draws fluid at the high rate, the fluid source10 experiences a reduced pressure on an outlet line. A pressuretransducer may be used to detect this pressure drop and increase thefluid generation rate accordingly. When the dialysis machine 30 reducesthe draw rate, the pressure on the outlet line of the fluid source 10will increase, which can be detected with the same pressure sensor,leading to a reduction in flow rate. This embodiment provides anothermeans of conveying flow rate information.

The data connection allows the flow rate of the fluid from the fluidsource 10 to be synchronized with the draw rate of the dialysis device30. This prevents the fluid source (such as system 60) from having toconsistently run at the peak draw rate of the dialysis machine 30. Thelife span of the components of the dialysis solution preparation system(such as pumps, filters, sensors, and so forth) can be extended byreducing their total use. Further, the fluid (whether dialysate orwater) that is produced but not used for dialysis (and thus wasted) islimited, because it is not pumped when it is not needed.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present subjectmatter and without diminishing its intended advantages. It is thereforeintended that such changes and modifications be covered by the appendedclaims.

1. A dialysis system comprising: a dialysis machine with a variablefluid demand including at least a lower demand and a higher demand; afluid source in fluid communication with the dialysis machine andproviding fluid to the dialysis machine at a fluid flow rate; and a flowregulation device comprising a fluid inlet in fluid communication withthe fluid source and a fluid outlet in fluid communication with thedialysis machine, wherein the flow regulation device is operable toexpand and contract to provide a variable internal volume, wherein theflow regulation device expands when the dialysis machine has the lowerdemand and contracts when the dialysis machine has the higher demand. 2.The dialysis system of claim 1 wherein the fluid is dialysate.
 3. Thedialysis system of claim 1 wherein the fluid is purified water.
 4. Thedialysis system of claim 1 wherein the flow regulation device comprisesa first wall and a second wall disposed opposite each other between thefluid inlet and the fluid outlet to define in part the internal volume,wherein the first wall and the second wall are composed of a compliantmaterial.
 5. The dialysis system of claim 4 wherein the first wall andthe second wall move away from each other when the device expands andmove towards each other when the device contracts.
 6. The dialysissystem of claim 1 wherein the flow regulation device comprises a pleatedwall, the pleated wall expanding outwardly and contracting inwardly toprovide the variable internal volume.
 7. The dialysis system of claim 1wherein the flow regulation device provides a maximum internal volumebetween 25 mL and 200 mL.
 8. The dialysis system of claim 7 wherein themaximum internal volume of the flow regulation device is between 50 mland 100 ml.
 9. The dialysis system of claim 1 wherein the fluid sourcecomprises a system for preparing the fluid from a water source.
 10. Thedialysis system of claim 1 wherein the fluid flow rate from the fluidsource is generally constant.
 11. The dialysis system of claim 10wherein the fluid flow rate from the fluid source is generally equal toan average fluid demand of the dialysis machine.
 12. The dialysis systemof claim 1 wherein the dialysis machine is a hemodialysis machine.
 13. Adialysis system comprising: a dialysis machine with a variable fluiddemand including at least a lower demand and a higher demand; a fluidsource in fluid communication with the dialysis machine and providingfluid to the dialysis machine at a fluid flow rate; and a flowregulation device comprising a fluid inlet in fluid communication withthe dialysis fluid source and a fluid outlet in fluid communication withthe dialysis machine, wherein the flow regulation device contains a gasproviding a gas volume, where the gas volume is regulated to provide avariable fluid volume, the flow regulation device providing a maximumfluid volume between 25 mL and 200 mL, wherein the gas volume decreaseswhen the dialysis machine has the lower demand and increases when thedialysis machine has the higher demand.
 14. The dialysis system of claim13 wherein the flow regulation device comprises a rigid canister. 15.The dialysis system of claim 13 wherein the gas volume is regulated bydischarging gas from the flow regulation device and taking gas into theflow regulation device.
 16. The dialysis system of claim 15 furthercomprising a filter for filtering gas entering the flow regulationdevice.
 17. A dialysis system comprising: a dialysis machine with avariable fluid demand; a fluid source in fluid communication with thedialysis machine and providing fluid to the dialysis machine at a fluidflow rate; a controller in communication with the dialysis machine andconfigured to send a control signal indicative of a fluid demand of thedialysis machine; and a flow control mechanism in communication with thecontroller and operable to receive the control signal to control thefluid flow rate based on the fluid demand of the dialysis machine. 18.The dialysis system of claim 14 wherein the control signal is providedby wire.
 19. The dialysis system of claim 14 wherein the control signalis provided wirelessly.
 20. A method of controlling the flow of fluid toa dialysis machine comprising: providing the dialysis machine, whereinthe dialysis machine has a variable fluid demand; providing a fluidsource in fluid communication with the dialysis machine and providingfluid to the dialysis machine; providing a flow control mechanism tocontrol flow from the fluid source; and controlling the flow of fluid tothe dialysis machine by sending a signal from the dialysis machine,wherein the signal is indicative of a fluid demand of the dialysismachine, and using the signal to regulate the flow control mechanism tocontrol the fluid flow based on the fluid demand of the dialysismachine.
 21. The method of claim 20 wherein the signal is indicative ofa current fluid demand of the dialysis machine.
 22. The method of claim20 wherein the signal is indicative of an anticipated future fluiddemand of the dialysis machine.
 23. The method of claim 20 wherein thedialysis machine comprises a pump and a pump controller, wherein thesignal is provided by the pump controller.
 24. The method of claim 20wherein the signal is provided by wire.
 25. The method of claim 20wherein the signal is provided wirelessly.